I have the following wix code
<Component Id='InfoKey' Directory='ProgramFilesFolder' Guid='{494493BF-F6E6-49EE-8C25-1C1C51CF2EE5}' Transitive='yes' KeyPath='no'>
<RegistryKey Action='createAndRemoveOnUninstall' Id='RegInfoKey' Root='HKLM' Key='Software\Acme\SuperProduct\Info'/>
</Component>
Which results that component doesn't have keypath at all. However it's legal to specify 'RegInfoKey' as key path for this component.
Also according to documentation the old Registry tag (which is deprecated) has KeyPath attribute and also can createKeyAndRemoveKeyOnUninstall
It was a bug that the WiX toolset allowed those types of registry keys to be KeyPaths. From the MSI SDK Component table topic on registry KeyPaths:
If the Value field of the corresponding record in the Registry table is null, the Name field in that record must not contain "+", "-", or "*".